I’ve tried mounting using nfsvers=3 and it seems to crash the mounts. They mount, but as soon as I try read or copy files from the mountpoint osmc locks up and I have to reboot. Removing the nfsvers=3 flag seems to resolve the issue. Mostly, I was trying to run nfsvers=3 and set the protocol to UDP as I have had good performance results with those flags on raspbmc.
So at present this works reliably for me:
192.168.x.x:/e/Videos/ /mnt/nfs-foo nfs lookupcache=none,noatime,rsize=32768,defaults,nolock,x-systemd.automount 0 0
However this seems to have problems:
192.168.x.x:/e/Videos/ /mnt/nfs-foo nfs nfsvers=3,proto=udp,lookupcache=none,noatime,rsize=32768,defaults,nolock,x-systemd.automount 0 0